Control of particulate flowback in subterranean wells

ABSTRACT

The present invention provides a method of treating a subterranean formation with a particulate laden fluid whereby particulate flowback is reduced or prevented. The method includes the steps of providing a fluid suspension including a mixture of a particulate, a tackifying compound and a hardenable resin, pumping the suspension into a subterranean formation and depositing the mixture within the formation whereby the tackifying compound retards movement of at least a portion of the particulate within the formation upon flow of fluids from the subterranean formation and said hardenable resin subsequently consolidates at least a portion of said particulate within said formation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application is a Continuation-in-part of U.S. applicationSer. No. 08/725,368, filed Oct. 3, 1996, now U.S. Pat. No. 5,787,986,which is a Continuation-in-Part of U.S. application Ser. No. 08/510,399,filed Aug. 2, 1995, now U.S. Pat. No. 5,582,249, which is aContinuation-in-Part of U.S. application Ser. No. 08/412,668 filed Mar.29, 1995, now U.S. Pat. No. 5,501,274.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to means for recovering hydrocarbons from asubterranean formation and more particularly to a method and means forcontrolling particulate solids transport during the production ofhydrocarbons from a subterranean formation.

2. Brief Description of the Prior Art

Transport of particulate solids during the production of hydrocarbonsfrom a subterranean formation is a continuing problem. The transportedsolids can erode or cause significant wear in the hydrocarbon productionequipment used in the recovery process. The solids also can clog or plugthe wellbore thereby limiting or completely stopping fluid production.Further, the transported particulates must be separated from therecovered hydrocarbons adding further expense to the processing.

The particulates which are available for transport may be present due toan unconsolidated nature of a subterranean formation and/or as a resultof well treatments placing particulates in a wellbore or formation, suchas, by gravel packing or propped fracturing.

In the treatment of subterranean formations, it is common to placeparticulate materials as a filter medium and/or a proppant in the nearwellbore area and in fractures extending outwardly from the wellbore. Infracturing operations, proppant is carried into fractures created whenhydraulic pressure is applied to these subterranean rock formations to apoint where fractures are developed. Proppant suspended in a viscosifiedfracturing fluid is carried outwardly away from the wellbore within thefractures as they are created and extended with continued pumping. Uponrelease of pumping pressure, the proppant materials remain in thefractures holding the separated rock faces in an open position forming achannel for flow of formation fluids back to the wellbore.

Proppant flowback is the transport of proppants back into the wellborewith the production of formation fluids following fracturing. Thisundesirable result causes undue wear on production equipment, the needfor separation of solids from the produced hydrocarbons and occasionallyalso decreases the efficiency of the fracturing operation since theproppant does not remain within the fracture and may limit the width orconductivity of the created flow channel. Proppant flowback often may bea aggravated by what is described as "aggressive" flowback of the wellafter a stimulation treatment. Aggressive flowback generally entailsflowback of the treatment fluid at a rate of from about 0.001 to about0.1 barrels per minute (BPM) per perforation of the treatment fluidswhich were introduced into the subterranean formation. Such flowbackrates accelerate or force closure of the formation upon the proppantintroduced into the formation. The rapid flowrate can result in largequantities of the proppant flowing back into the wellbore before closureoccurs or where inadequate bridging within the formation occurs. Therapid flowback is highly desirable for the operator as it returns awellbore to production of hydrocarbons significantly sooner than wouldresult from other techniques.

Currently, the primary means for addressing the proppant flowbackproblem is to employ resin-coated proppants or resin consolidation ofthe proppant which are not capable of use in aggressive flowbacksituations. Further, the cost of resin-coated proppant is high, and istherefore used only as a tail-in in the last five to twenty five percentof the proppant placement. Resin-coated proppant is not always effectivesince there is some difficulty in placing it uniformly within thefractures. Another means showing reasonable effectiveness has been togradually release fracturing pressure once the fracturing operation hasbeen completed so that fracture closure pressure acting against theproppant builds slowly allowing the proppant particles to stabilizebefore flowback of the fracturing fluid and the beginning of hydrocarbonproduction. Such slow return is undesirable, however, since it reducesthe production from the wellbore until the treatment fluid is removed.

In unconsolidated formations, it is common to place a filtration bed ofgravel in the near-wellbore area in order to present a physical barrierto the transport of unconsolidated formation fines with the productionof hydrocarbons. Typically, such so-called "gravel packing operations"involve the pumping and placement of a quantity of gravel and/or sandhaving a mesh size between about 10 and 60 mesh on the U.S. StandardSieve Series into the unconsolidated formation adjacent to the wellbore.It is sometimes also desirable to bind the gravel particles together inorder to form a porous matrix through which formation fluids can passwhile straining out and retaining the bulk of the unconsolidated sandand/or fines transported to the near wellbore area by the formationfluids. The gravel particles may constitute a resin-coated gravel whichis either partially cured and subsequently completes curing or can becured by an overflush of a chemical binding agent once the gravel is inplace. It has also been known to add various hardenable binding agentsor hardenable adhesives directly to an overflush of unconsolidatedgravel in order to bind the particles together.

U.S. Pat. Nos. 5,330,005, 5,439,055 and 5,501,275 disclose a method forovercoming the difficulties of resin coating proppants or gravel packsby the incorporation of a fibrous material in the fluid with which theparticulates are introduced into the subterranean formation. The fibersgenerally have a length ranging upwardly from about 2 millimeters and adiameter of from about 6 to about 200 microns. Fibrillated fibers ofsmaller diameter also may be used. The fibers are believed to act tobridge across constrictions and orifices in the proppant pack and form amat or framework which holds the particulates in place thereby limitingparticulate flowback. The fibers typically result in a 25 percent orgreater loss in permeability of the proppant pack that is created incomparison to a pack without the fibers.

While this technique may function to limit some flowback, it fails tosecure the particulates to one another in the manner achieved by use ofresin coated particulates.

U.S. Pat. No. 5,501,274 discloses a method for reducing proppantflowback by the incorporation of thermoplastic material in particulate,ribbon or flake form with the proppant. Upon deposition of the proppantand thermoplastic material in the formation, the thermoplastic materialsoftens and causes particulates adjacent the material to adhere to thethermoplastic creating agglomerates. The agglomerates then bridge withthe other agglomerates and other particulates to prevent flowback fromthe formation.

It would be desirable to provide a more permanent method which will bindgreater numbers of particles of the particulate to one another wherebyagglomerates may be formed which would further assist in preventingmovement or flowback of particulates from a wellbore or formationwithout significantly reducing the permeability of the particulate packduring aggressive flowback of treatment fluids.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method and fluid for treating asubterranean formation and a resultant porous particulate pack thatinhibits the flow of particulates back through the wellbore during theproduction of hydrocarbons without significant effects upon thepermeability of the particulate pack.

In accordance with the invention, a method of treating a subterraneanformation penetrated by a wellbore is provided comprising the steps ofproviding a fluid suspension including a mixture of particulatematerial, a material comprising a liquid or solution of a tackifyingcompound, which coats at least a portion of the particulate uponadmixture therewith, and a hardenable resin, which coats or is coatedupon at least a portion of the particulate, pumping the fluid suspensionincluding the coated particulate through the wellbore and depositing themixture in the formation. Upon deposition of proppants having beencoated with the tackifying compound and resin material mixture in theformation the coating causes particulate adjacent to the coated materialto adhere to the coated material thereby creating proppant agglomerateswhich bridge against other particles in the formation to minimizeinitial particulate flowback and the hardenable resin subsequentlyconsolidates the particulate before and during flowback.

The coated material is effective in inhibiting the flowback ofparticulate in a porous pack having a size ranging from about 2 to about400 mesh in intimate admixture with the tackifying compound andhardenable resin coated particulates.

The coated material is effective in consolidating particulate into theform of agglomerates in a formation as a result of a fracturing orgravel packing treatment performed on a subterranean formation duringaggressive flowback of the treatment fluid.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, a liquid or solution of atackifying compound is incorporated in an intimate mixture with aparticulate material such as conventional proppants or gravel packingmaterials together with a hardenable resin and introduced into asubterranean formation.

As used in this specification, the term "intimate mixture" will beunderstood to mean a substantially uniform dispersion of the componentsin the mixture. The term "simultaneous mixture" will be understood tomean a mixture of components that are blended together in the initialsteps of the subterranean formation treatment process or the preparationfor the performance of the treatment process.

The coated particulate or proppant material may comprise substantiallyany substrate material that does not undesirably chemically interactwith other components used in treating the subterranean formation. Thematerial may comprise sand, ceramics, glass, sintered bauxite, resincoated sand, resin beads, metal beads and the like. The coated materialalso may comprise an additional material that is admixed with aparticulate and introduced into a subterranean formation to reduceparticulate flowback. In this instance the additional substrate materialmay comprise glass, ceramic, carbon composites, natural or syntheticpolymers or metal and the like in the form of fibers, flakes, ribbons,beads, shavings, platelets and the like. In this instance, theadditional substrate material generally will be admixed with theparticulate in an amount of from about 0.1 to about 5 percent by weightof the particulate. The tackifying compound comprises a liquid or asolution of a compound capable of forming at least a partial coatingupon the substrate material with which it is admixed prior to orsubsequent to placement in the subterranean formation. In someinstances, the tackifying compound may be a solid at ambient surfaceconditions and upon initial admixing with the particulate and afterheating upon entry into the wellbore for introduction into thesubterranean formation become a melted liquid which at least partiallycoats a portion of the particulate. Compounds suitable for use as atackifying compound comprise substantially any compound which when inliquid form or in a solvent solution will form a non-hardening coating,by themselves, upon the particulate which facilitates agglomeration andwill increase the continuous critical resuspension velocity of theparticulate when contacted by a stream of water as hereinafter describedin Example I by at least about 50 percent over the particulate alonewhen present in a 0.5 percent by weight active material concentrationand increase the initial critical resuspension velocity by at leastabout 50 percent over the particulate alone. Preferably, the continuouscritical resuspension velocity is increased by at least 100 percent overparticulate alone and most preferably at least about 150 percent overparticulate alone and the initial critical resuspension velocity isincreased by at least 75 percent and most preferably at least 100percent over particulate alone. A particularly preferred group oftackifying compounds comprise polyamides which are liquids or in solventsolution at the temperature of the subterranean formation to be treatedsuch that the polyamides are, by themselves, non-hardening when presenton the particulates introduced into the subterranean formation. Aparticularly preferred product is a condensation reaction productcomprised of commercially available polyacids and a polyamine. Suchcommercial products include compounds such as mixtures of C₃₆, dibasicacids containing some trimer and higher oligomers and also small amountsof monomer acids which are reacted with polyamines. Other polyacidsinclude trimer acids, synthetic acids produced from fatty acids, maleicanhydride and acrylic acid and the like. Such acid compounds areavailable from companies such as Witco, Union Camp, Chemtall, and EmeryIndustries. The reaction products are available from, for example,Champion Chemicals, Inc. and Witco.

In general, the polyamides of the present invention are commerciallyproduced in batchwise processing of polyacids predominately having twoor more acid functionalities per molecule with a polyamine. As is wellknown in the manufacturing industry, the polyacids and polyfunctionalamines are introduced into a reactor where, with agitation, the mildlyexothermic formation of the amine salt occurs. After mixing, heat isapplied to promote endothermic dehydration and formation of the polymermelt by polycondensation. The water of reaction is condensed and removedleaving the polyamide. The molecular weight and final properties of thepolymer are controlled by choice and ratio of feedstock, heating rate,and judicious use of monofunctional acids and amines to terminate chainpropagation. Generally an excess of polyamine is present to preventrunaway chain propagation. Unreacted amines can be removed bydistillation, if desired. Often a solvent, such as an alcohol, isadmixed with the final condensation reaction product to produce a liquidsolution that can readily be handled. The condensation reactiongenerally is accomplished at a temperature of from about 225° F. toabout 450° F. under a nitrogen sweep to remove the condensed water fromthe reaction. The polyamines can comprise, for example, ethylenediamine,diethylenetriamine, triethylene tetraamine, amino ethyl piperazine andthe like.

The polyamides can be converted to quaternary compounds by reaction withmethylene chloride, dimethyl sulfate, benzylchloride, diethyl sulfateand the like. Typically the quaternization reaction would be effected ata temperature of from about 100° to about 200° F. over a period of fromabout 4 to 6 hours.

The quaternization reaction may be employed to improve the chemicalcompatibility of the tackifying compound with the other chemicalsutilized in the treatment fluids. Quaternization of the tackifyingcompound can reduce effects upon breakers in the fluids and reduce orminimize the buffer effects of the compounds when present in variousfluids.

Additional compounds which may be utilized as tackifying compoundsinclude liquids and solutions of, for example, polyesters andpolycarbamates, polycarbonates, natural resins such as shellac and thelike.

The tackifying compound is admixed with the particulate in an amount offrom about 0.1 to about 3.0 percent active material by weight of thecoated particulate. It is to be understood that larger quantities may beused, however, the larger quantities generally do not significantlyincrease performance and could undesirably reduce the permeability ofthe particulate pack. Preferably, the tackifying compound is admixedwith the particulate introduced into the subterranean formation in anamount of from about 0.25 to about 2.0 percent by weight of the coatedparticulate.

When the tackifying compound is utilized with another material that isto be admixed with the particulate and which is to be at least partiallycoated with the tackifying compound, such as glass fibers or the like,the compound is present in an amount of from about 10 to about 250percent active material by weight of the glass fibers or other addedmaterial and generally from about 0.1 to about 3 percent active materialby weight of the quantity of particulate with which the coated materialis intimately admixed. Preferably the tackifying compound is present inan amount of from about 50 to about 150 percent of the material which isto be at least partially coated with the tackifying compound and thenadded to the particulate. At least a portion of the tackifying compoundintroduced with the additional material will contact and coat at least aportion of the particulate with which it is admixed.

The hardenable resin comprises an epoxy or phenolic resin or othercompound capable of being at least partially coated upon a particulatesubstrate and then cured to a higher degree of polymerization. Examplesof such resins include phenol-aldehyde resins of both the resole andnovolac type, urea-aldehyde resins, melamine-aldehyde resins, epoxyresins, furfuryl alcohol resins and the like. The curing may result fromheating the resin to a higher temperature such as can occur with theresole resins or by the addition of a catalyst or crosslinker to theresin which initiates polymerization. Admixtures of resins such as theresole and novalac resins may be utilized wherein sufficient resoleresin is incorporated to initiate polymerization in the novalac resin.Various resins are described in for example U.S. Pat. Nos. 5,420,174;5,218,038; 5,425,994 and 4,888,240 the entire disclosures of which areincorporated herein by reference thereto. Particularly preferred resinsinclude epoxy resins such as "EPON 828" epoxy resin from Shell ChemicalCompany, Houston, Tex. Phenolic resins such as "Resin 1866" from AcmeResin Corporation, Borden Division, Forrest Park, Ill., furan resinssuch as "ARS-1500" resin from Advanced Resin Systems, Des Plains, Ill.and novalac Resins such as "Bakelite 9282 FP" resin also available fromAdvanced Resin Systems.

The resin is admixed with the particulate in an amount of from about0.01 to about 5.0 percent by weight of the particulate. Preferably, theresin is admixed with the particulate in an amount of from about 0.05about 1.0 percent by weight of the particulate. Curing agents, catalystsor crosslinkers selected from those well known in the art may beutilized with the resin to harden the resin and form a consolidatedmatrix of particulate.

The liquid or solution of tackifying compound interacts mechanicallywith the particles of particulate introduced into the subterraneanformation to limit or prevent the flowback of particulates to thewellbore during initial flowback prior to hardening and consolidation ofthe particulates by the hardenable resin.

In one embodiment, the tackifying compound, when comprised ofpolyamides, may be admixed and contacted with a material that hasmulti-functional reactive sites which are capable of reacting with thetackifying compound to form a hard reaction product which consolidatesthe agglomerates formed by the tackifying compound. A "hard reactionproduct" as used herein means that the reaction of the tackifyingcompound with the multifunctional material will result in asubstantially nonflowable reaction product that exhibits a highercompressive strength in a consolidated agglomerate than the tackifyingcompound alone with the particulates. One means of evaluating theconsolidated agglomerate to determine whether an increase in compressivestrength has occurred is through testing with a penetrometer. Samplesmay be prepared comprising particulate coated with the tackifyingcompound, multifunctional material and an admixture as described hereinand penetrometer readings can be made using equipment such as a PWGPenetrometer from Precision Scientific Company, Chicago, Ill. Comparisonof the penetrometer readings readily demonstrates the change that hasoccurred as a result of the reaction. In this instance, the tackifyingcompound also functions as the hardenable resin. The material havingmulti-functional reactive sites include compounds such as aldehydes suchas formaldehyde, dialdehydes such as glutaraldehyde, hemiacetals oraldehyde releasing compounds, diacid halides, dihalides such asdichlorides and dibromides, polyacid anhydridesa such as citric acid,epoxides and the like. Preferred compounds for use with polyamidescomprise furfuraldehyde, glutaraldehyde or aldehyde condensates and thelike. The multi-functional compound is admixed with the tackifyingcompound in an amount of from about 0.01 to about 50 percent by weightof the tackifying compound to effect formation of the reaction product.Preferably, the compound is present in an amount of from about 0.5 toabout 1 percent by weight of the tackifying compound.

The liquid or solution of tackifying compound and hardenable resingenerally are incorporated with the particulate in any of theconventional fracturing or gravel packing fluids comprised of an aqueousfluid, an aqueous foam, a hydrocarbon fluid or an emulsion, aviscosifying agent and any of the various known breakers, buffers,surfactants, clay stabilizers or the like.

Generally the tackifying compound and hardenable resin may beincorporated into fluids having a pH in the range of from about 3 toabout 12 for introduction into a subterranean formation. The compoundsare useful in reducing particulate movement within the formation attemperatures from about ambient to in excess of 300° F. It is to beunderstood that not every hardenable resin or tackifying compound willbe useful over the entire pH or temperature range but every compound isuseful over at least some portion of the range and individuals canreadily determine the useful operating range for various productsutilizing well known tests and without undue experimentation.

The liquid or solution of tackifying compound and the hardenable resingenerally are incorporated with the particulate as a simultaneousmixture by introduction into the fracturing or gravel packing fluidalong with the particulate. Fracturing fluid slurries are introducedinto the subterranean formation at a rate and pressure sufficient tocreate at least one fracture in the formation into which particulatethen is introduced to prop the created fracture open to facilitatehydrocarbon production. Gravel packing treatments generally areperformed at lower rates and pressures whereby the fluid can beintroduced into a formation to create a controlled particule size packsurrounding a screen positioned in the wellbore where fracturing of theformation may or may not occur. The particulate pack surrounding thewellbore then functions to prevent fines or formation particulatemigration into the wellbore with the production of hydrocarbons from thesubterranean formation.

The gravel packing treatment also may be performed without a screen inthe wellbore. In such a screenless completion, the fluid generally isintroduced into the wellbore to fill the perforations and wellbore to alevel above the perforations and permitted to consolidate. Theconsolidated pack can then be drilled or reamed out to reopen the borewhile providing a consolidated pack to screen fines and formationparticulate from migrating into the wellbore.

The tackifying compound may be introduced into the fluid before, afteror simultaneously with introduction of the particulate into the fluid.The liquid or solution may be incorporated with the entire quantity ofparticulate introduced into the subterranean formation or it may beintroduced with only a portion of the particulate, such as in the finalstages of the treatment to place the intimate mixture in the formationin the vicinity of the wellbore. For example, the tackifying compoundmay be added to only the final 20 to 30 percent of the particulate ladenfluid introduced into the formation and the hardenable resin may beadded to only the last 10 to 20 percent of the particulate laden fluid.In this instance, the intimate mixture will form a tail-in to thetreatment which upon interaction within the formation with theparticulate will cause the particles to bridge on the agglomeratesformed therein and prevent movement of the particles into the wellborewith any produced fluids. The tackifying compound and hardenable resinmay be introduced into the blender or into any flowline in which theywill contact the material to be at least partially coated by thecompounds. The compounds may be introduced with metering pumps or thelike prior to entry of the treatment fluid into the subterraneanformation.

In an alternate embodiment, the particulate may be premixed with eitherthe tackifying compound or the hardenable resin prior to admixing with atreatment fluid and the other constituents for use in a subterraneanformation. In some instances, resin precoated particulates may beutilized and the tackifying compound then would be added duringperformance of the subterranean formation treatment. Depending upon thetype of resin coating employed, a catalyst then would be added to thetreatment fluid or introduced in a flush fluid or the like.

Surprisingly, it has been found that use of the method of the presentinvention can produce high permeability tunnels extending from wellboreperforations back into proppant packed fractures created in thesubterranean formation which then may be consolidated. Control of theflowback rate of the treatment or formation fluids from the wellbore canbe used to provide a controlled erosion of the treated particulateimmediately adjacent a perforation in the wellbore. The flowback rate iscontrolled so as to provide a level above the initial criticalresuspension velocity of the tackifying compound but generally ismaintained below the continuous critical resuspension velocity. Thisresults in controlled production of particulate from the formation. Theerosion surprisingly has been found to be very uniform in nature and tocreate a tunnel into the particulate in the formation generallycorresponding to the size and shape of the perforation in the wellbore.After the tunnel is formed, the hardenable resin consolidates theremaining particulate to provide a high permeability passage or tunnelfrom the formation to the wellbore.

To further illustrate the present invention and not by way oflimitation, the following examples are provided.

EXAMPLE I

The evaluation of a liquid or solution of a compound for use as atackifying compound is accomplished by the following test. A criticalresuspension velocity is first determined for the material upon whichthe tackifying compound is to be coated. The apparatus comprises a 1/2"glass tee which is connected to an inlet source of water and an outletdisposal line is blocked to fluid flow. A water slurry of particulate isaspirated into the tee through inlet and collected within a lowerportion of said tee by filtration against a screen. When the lowerportion of the tee is full, the vacuum source is removed and a plug isused to seal the end of the lower portion of the tee. The flow channelfrom inlet to outlet then is swabbed clean and a volumetricallycontrolled pump, such as a "MOYNO" pump, is connected to the inlet and acontrolled flow of water is initiated. The velocity of the fluid isslowly increased through the inlet until the first particule ofparticulate material is picked up by the flowing water stream. Thisdetermines the baseline for the starting of the resuspension velocity.The flow rate then is further increased until the removal of particlesbecomes continuous. This determines the baseline for the continuousresuspension velocity. The test then is terminated and the apparatus isrefilled with particulate having a coating corresponding to about 0.5percent active material by weight of the particulate applied thereto.Similar trends generally are seen in the results when the concentrationstested are from about 0.1 to about 3 percent, however, the 0.5 percentlevel which is within the preferred application range is preferred forstandardization of the procedure. The test is repeated to determine thestarting point of particulate removal and the velocity at which removalbecomes continuous. The percent of velocity increase (or decrease) thenis determined based upon the initial or continuous baseline value. Theresults of several tests employing the preferred polyamide of thepresent invention, and conventional epoxy and phenolic resins known foruse in consolidation treatments in subterranean formations with 12/20and 20/40 mesh sand are set forth below in Table I.

                  TABLE I                                                         ______________________________________                                                          Percent Of Velocity                                                           Change At:                                                                  Coating Agent,                                                                            Starting of                                                                           Continuous                                Test  Particulate                                                                             % V/Wt      Sand Particle                                                                         Sand                                      No.   Size      Particulate Transport                                                                             Transport                                 ______________________________________                                        1     20/40/mesh                                                                              none        0                                                       sand                                                                    2     20/40 mesh                                                                              1/2 percent 192     222                                             sand      polyamide                                                     3     20/40 mesh                                                                              1 percent   271     391                                             sand      polyamide                                                     4     20/40 mesh                                                                              1/2 percent -0.5    6.5                                             sand      phenolic                                                      5     20/40 mesh                                                                              1 percent   -9      -6.8                                            sand      phenolic                                                      6     20/40 mesh                                                                              1/2 percent -9      -1.2                                            sand      epoxy                                                         7     20/40 mesh                                                                              1 percent   5.2     12.2                                            sand      epoxy                                                         8     12/20 mesh                                                                              1/2 percent 228     173                                             sand      polyamide                                                     9     12/20 mesh                                                                              1 percent   367     242                                             sand      polyamide                                                     10    12/20 mesh                                                                              1/2 percent 42      22                                              sand      phenolic                                                      11    12/20 mesh                                                                              1 percent   42      13                                              sand      phenolic                                                      12    12/20 mesh                                                                              1/2 percent 48      30                                              sand      epoxy                                                         13    12/20 mesh                                                                              1 percent   38      15                                              sand      epoxy                                                         ______________________________________                                    

The data clearly illustrates the substantial increase in the criticalresuspension velocity of a particulate coated with the tackifyingcompound in comparison to other known formation consolidation agentswhich require hardening to be effective.

The test results clearly demonstrate the beneficial results achieved bypractice of the method of the present invention with respect to proppantproduction from a simulated formation.

EXAMPLE II

The stabilization properties of the method of the present invention aredetermined by comparison to untreated sand and sand including atackifying compound. The flowback velocity is measured in an AmericanPetroleum Institute approved simulated fracture flow cell. The cellcontains Ohio sandstone cores having a proppant bed size of about 1.5inches in height, about 7 inches in length and about 0.25 inches inwidth between the cores. The bed is initially prepacked with 20/40 meshsand by introducing the sand into the cell in an aqueous slurry or agelled fluid containing 40 pounds of guar per 1000 gallons of aqueousfluid. The cell is fitted with a 0.3 inch hole at one end to simulate aperforation. The hole is visible through a sight glass so that proppantproduction through the hole can be visually determined.

The cell then was cleaned and packed with another proppant pack fortesting. The tested materials are set forth in Table II, below.

While the present invention has been described with regard to that whichis currently considered to comprise the preferred embodiments of theinvention, other embodiments have been suggested and still otherembodiments will occur to those individuals skilled in the art uponreceiving the foregoing specification. It is intended that all suchembodiments shall be included within the scope of the present inventionas defined by the claims appended hereto.

                  TABLE II                                                        ______________________________________                                                         ADDITIVES TO  FLOW RATE,                                            PACKING   SAND, % BY WT.                                                                              ml/min AT WHICH                                SAMPLE FLUID     SAND          FAILURE OCCURS                                 ______________________________________                                        1      water     none           84                                            2      gel       none           90                                            3      gel       1% by wt       180                                                            polyamide                                                    4      gel       2% by wt       384                                                            polyamide                                                    5      gel       1% by wt      >3000.sup.1                                                     polyamide and 1%                                                              out Bakelite 9282                                                             FP resin                                                     6      gel       1% by wt      >2600.sup.2                                                     polyamide and 1%                                                              by wt Bakelite                                                                9282 FP resin                                                ______________________________________                                         .sup.1 pack heated at 250° F. for 72 hours before testing, no sand     production during test                                                        .sup.2 pack heated at 180° F. for 4 hours before testing no sand       production during test                                                   

What is claimed is:
 1. A method of treating a subterranean formationcomprising the steps of:introducing a particulate-containing fluidsuspension into a subterranean formation; admixing with at least aportion of said particulate in said fluid suspension a liquid orsolution of a tackifying compound whereby at least a portion of saidparticulate is at least partially coated by said compound; admixing withat least a portion of said particulate in said fluid suspension ahardenable resin whereby at least a portion of said particulate is atleast partially coated by said resin; depositing the tackifying compoundand hardenable resin coated particulates in the subterranean formation;and flowing back fluid from the formation whereby the tackifyingcompound coated particulate retards movement of at least a portion ofthe particulate within said formation and said hardenable resinsubsequently consolidates at least a portion of the particulate withinsaid formation.
 2. The method of claim 1 wherein said tackifyingcompound comprises predominately a condensation reaction product of adimer acid containing some trimer and higher oligomers and some monomeracids with a polyamine.
 3. The method of claim 2 wherein said polyaminecomprises at least one member selected from the group ofethylenediamine, diethylenetriamine, triethylenetetraamine,tetraethylene pentaamine and aminoethylpiperazine.
 4. The method ofclaim 1 wherein said hardenable resin comprises at least one memberselected from the group of phenol-aldehyde resins, urea-aldehyde resins,melamine-aldehyde resins, epoxy resins and furfuryl alcohol resins. 5.The method of claim 1 wherein said hardenable resin is a reactionproduct of the tackifying compound and a multifunctional materialcomprising at least one member selected from the group of dialdehydes,diacid halides, dihalides, and polyacid anhydrides.
 6. A method oftreating a subterranean formation comprising the steps of:introducing atreatment fluid into a subterranean formation; admixing with at least aportion of said fluid, a particulate which is introduced into anddeposited within said formation; admixing with at least a portion ofsaid particulate a liquid or solution of a tackifying compound wherebyat least a portion of said particulate is at least partially coated bysaid compound such that the critical resuspension velocity of said atleast partially coated particulate is increased by at least about 50percent when tested at a level of 0.5% active material by weight oversaid particulate alone with water; admixing with at least a portion ofsaid particulate in said treatment fluid a hardenable resin whereby atleast a portion of said particulate is at least partially coated by saidresin; depositing the tackifying compound and hardenable resin coatedparticulates in the subterranean formation; and flowing back fluid fromthe formation whereby the tackifying compound coated particulate retardsmovement of at least a portion of the particulate within said formationand said hardenable resin subsequently consolidates at least a portionof the particulate within said formation.
 7. The method of claim 6wherein said tackifying compound is admixed with said particulate in anamount of from about 0.1 to about 3.0 percent by weight of saidparticulate.
 8. The method of claim 6 wherein said tackifying compoundis admixed with said particulate in an amount of from about 0.25 toabout 2 percent by weight of said particulate.
 9. The method of claim 6wherein said coated particulate has a critical resuspension velocity inexcess of 100 percent over said particulate alone.
 10. The method ofclaim 6 wherein said tackifying compound comprises a liquid or solutionof a polyamide.
 11. The method of claim 6 wherein said tackifyingcompound comprises predominately a condensation reaction product of adimer acid containing some trimer and higher oligomers and some monomeracids with a polyamine.
 12. The method of claim 11 wherein saidpolyamine comprises at least one member selected from the group ofethylenediamine, diethylenetriamine, triethylenetetraamine,tetraethylene pentaamine and aminoethylpiperazine.
 13. The method ofclaim 11 wherein said tackifying compound has been quaternized.
 14. Themethod of claim 6 wherein said hardenable resin comprises at least onemember selected from the group of phenol-aldehyde resins, urea-aldehyderesins, melamine-aldehyde resins, epoxy resins and furfuryl alcoholresins.
 15. The method of claim 6 wherein said hardenable resin is areaction product of the tackifying compound and a multifunctionalmaterial comprising at least one member selected from the group ofdialdehydes, diacid halides, dihalides, and polyacid anhydrides.
 16. Amethod of treating a subterranean formation penetrated by a wellborecomprising the steps of:providing a fluid suspension including a mixtureof a particulate material and another material selected from the groupof particles comprising metal, natural or synthetic polymers, ceramicsand glass which are at least partially coated with a liquid or solutionof a tackifying compound and a hardenable resin; introducing the fluidsuspension into a subterranean formation through a wellbore; depositingthe fluid suspension in the formation; and flowing back fluid from theformation whereby the tackifying compound material retards movement ofat least a portion of the particulate material from the formation intothe wellbore and said hardenable resin subsequently consolidates atleast a portion of the particulate material within said formation. 17.The method of claim 16 wherein said another material is in the form offibers, beads, ribbons, flakes, platelets or shavings.
 18. The method ofclaim 16 wherein said another material is present in an amount of fromabout 0.1 to about 5% by weight of the particulate material.
 19. Themethod of claim 16 wherein said tackifying compound is present in anamount of from about 0.1 to about 3% by weight of said particulate. 20.The method of claim 16 wherein said tackifying compound comprises aliquid or solution of a polyamide.
 21. The method of claim 16 whereinsaid hardenable resin comprises at least one member selected from thegroup of phenol-aldehyde resins, urea-aldehyde resins, melamine-aldehyderesins, epoxy resins and furfuryl alcohol resins.
 22. The method ofclaim 16 wherein said tackifying compound at least one member selectedfrom the group of a liquid or solution of a polyester, a polycarbonatepolycarbamate and a natural resin.
 23. A method of treating asubterranean formation penetrated by a wellbore having perforationstherein comprising the steps of:introducing a particulate-containingfluid into a subterranean formation; admixing with at least a portion ofsaid particulate in said fluid suspension a liquid or solution of atackifying compound whereby at least a portion of said particulate is atleast partially coated by said compound; providing a quantity of ahardenable resin coated particulate in said fluid suspension; depositingthe tackifying compound and hardenable resin coated particulates in thesubterranean formation controllably flowing back fluid from thesubterranean formation whereby erosion tunnels are formed in theparticulate deposited in the formation adjacent the perforations; andconsolidating said particulates in said formation by subsequenthardening of said hardenable resin whereby high permeability flowtunnels are produced which connect said formation with said wellbore.24. The method of claim 23 wherein said tackifying compound comprises aliquid or solution of a polyamide.
 25. The method of claim 23 whereinsaid hardenable resin is a reaction product of the tackifying compoundand a multifunctional material comprising at least one member selectedfrom the group of aldehydes, dialdehydes, hemiacetals, diacid halides,dihalides, epoxides, and polyacid anhydrides.